Dear Mr. Dad: I'm a single dad – my wife left me with the baby right after our son was born. He's now four and keeps asking where his mommy is. I try to keep in touch with her and ask her to spend time with her son, but she's not interested. I've also been dating a lot, hoping to meet women so my son can have some positive female role models in his life, but no luck yet. My son clearly wants a mom. But what I'm most worried about is that he's not sleeping, eating, or behaving like other kids his age. What should I do?